Butt contact rotary switch



May 10, 1938. H. E. METCALF BUTT CONTACT ROTARY SWITCH Filed se t'. 7,1957 IN VEN TOR,

Patented Mi, 10, 1938 UNITED STATES.

BUTT CONTACT ROTARY SWITCH Herbert E. Metcalf, Walnut Creek, Calif., as-

signor to E. H. Kaefier, Oakland, Calif.

Application September 1, 1931, Serial No. 162,636

3Claims.

-My invention relates .to rotary switches, and more particularly to arotary switch which will indicate by making and breaking an electricalcircuit, the direction of rotation'of a shaft. Y

In the Clarence B. Howard United States Patent No. 2,096,745, issuedOctober 26,1937, the inventor has described certain forms of rotaryswitchesoperating signalling systems upon reversal of direction ofrotation of a shaft, and the switches embodied therein all utilizesliding contacts, inasmuch as butt contacts have hitherto beenimpractical when usedin conjunction with rotary switches of this type,as will be seen here- .inaften' f My present invention has, for its mainobject. the provision of a switch wherein butt contacts may be used andsupported in. such amanner that the electrical circuits, when made andbroken, are definitely controlled, and not subject to theirregularities, arcing, imperfect contacts, etc. of the usual type ofbutt contact switch.

Other objects of my invention will be apparent or will be specificallypoin'ted'out in the descril tion forming apart of this specification,but I do not limit myself to the embodiment of the invention hereindescribed, as various forms may be adopted within the scope of theclaims.

- In the more common form of shaft reversal indicating switch, afriction driven arm is mounted on the shaft to be" rotated and the endof this arm carries a contact point. A second contact point is fixedlypositioned in the path of rotation of the first contact to that as theshaft is rotated in one direction, these contacts will be forced to- Igether in face-to-face relationship, the Dressure of contact beingderived wholly from the frictional connection with the shaft.

Such a device is only satisfactory where the shaft is rotating atrelatively high speeds, be-

40 cause when the shaft speed is reduced the frictional forces holdingthe contact points together decrease, and when the shaft stops, withoutreversal'of rotation, there is no force holding the opposing faces ofthe contact points together. slightest jolt or other motion causesarcing of the contact faces, and minute rotations of the shaft cause acontinual making and breaking of the electrical contact. Under theseconditions thecontaetsareveryeasilydestmyed,andthegoindication'obtainedcannotbe reliednponbecaused the imperfect contact.Furthermore, theretnowaypoisiblewithsuchswitchestoalhwcontactduringashortpathofreversaiof the shaft to allow forminorvariations in rotation 3 without changing the indication.

I have therefore provided a switch, several modifications of which areillustrated herein, where butt contacts are used and where at least oneof these contacts is resiliently supported so that when shaft rotation,stops the resiliency of g the support maintains the contact,irrespective of the stopping, and even of minor reversals of directionof rotation of the shaft.

Other broad objects of my invention may be drawing, wherein Fig. 1 is aview partly in section and partly in elevation of a butt contact switchof the char-' acter described, wherein a friction controlled disc isutilized. 1|

Fig. 2 is a view partly in section and partly in plan, taken asindicated by the line 2-2 in Fig. 1. Fig. 3 is a view partly in sectionand partly in elevation of an optional method of resiliently supportingone of the contacts.

Fig. 4 is a view partly in sectionand partly in elevation of amodification utilizing a friction driven arm for operating the shaft.

Fig. 5 is a view partly in section and partly in elevation, taken asindicated by the line 5-5 in Fig. 4. 1

Fig. 6 is a view partly in sectionand partly in elevation of an optionalarrangement of contacts. The switch shown in detail in Figs. 1, 2, and 3utilizes a friction controlled disc. In this type of switch a case Iprovides spaced bearings for an operating shaft 2. Inside the case thereis a collar 3 fixed to the shaft, and against this collar is positioneda contact disc 4, preferably of insulating material, and having a metalperiphery I. Hie periphery carries a contact point 8 extending outtherefrom, in the path of a resiliently supported contact I projectingfrom an insulating sleeve I pinned to the shaft, this sleeve beingprovided with a raised slip ring 9. Backing up 44) the resilientlysupported contact I is a rotating arm ll.

The friction brush 1 I. supported by brush studs II from the case, bearsagainst the metal periphery i of the disc 4, and a circuit brush it 45bears against slip ring 9. The resiliently supported contact I isconnected to the slip ring I' through a metal link i5. Thus, when theresilient contact I touches peripheral contact 0 on disc 4, electricalconnection will be made be- It) tween friction brush stud If and slipring brush stud It, both of these studs being insulated from the case bybushings l1.

The operation of the switch to indicate direction of rotation by makingand breaking elecf trical contact is as follows: When shaft 2 is rotatedso that the resiliently supported contact 'I approaches peripheralcontact 6, nothing will happen in the switch until contact I touchescontact 6 to establish electrical circuit through the switch. Pressurewill then be exerted by the resiliently supported contact 1 againstperipheral contact 6 to cause rotation of disc 4. I prefer, however, toprevent such rotation by adjusting the pressure of friction brush llagainst periphery 5, so that instead of the disc rotating, contact Iwill flex and continue to flex until the rigid arm I touches and backsup contact 1, thus limiting the flexure by preventing further flexure,and positively rotating the disc against the friction developed betweenperiphery 5 and brush ii. Thus, all during the rotation in the originaldirection electrical contact will be made through the switch.

When the shaft 2 stops rotating, arm ID will no longer exert a pressureagainst resilient contact l and peripheral contact 6, and in theordinary butt switch using no resiliently supported contact, theelectrical connection through the switch at this particular positionwould be poor, arcing would take place, and imperfect connection wouldbe inevitable. However, under these circumstances, and in the switchjust described, the resilient support of contact I continues to pressagainst contact 6 and the electrical connection is maintained firm. Atthe same time, arm 30 may move in the reverse direction over a distanceequal to the normal divergence of contact l from arm iii before theelectrical connection will be broken. If, however, arm ill moves in thereverse direction a greater distance, contact I will then breakconnection with contact 6 and this break will be maintained until thedirection of rotation of the shaft is again reversed.

In order that the arm l0 and contact I may not travel too far away fromcontact point 6, a stop pin l8 is provided on disc 4, so that uponrotation in the reverse direction the arm ill will hit the stop pin l8and the arm and disc will rotate together. It is obvious that thedistance the two contacts may diverge from each other, and the distanceover which they will remain in contact with each other before beingbacked up by arm l0, may be readily adjusted by theposition of pin I8 inone instance and the divergence of contact I from the arm Ill in theother instance.

While in Figs. 1 and 2 I have shown the contact point I supported by aresilient arm extending substantially radially from shaft 2, it isobvious that this contact may also be resiliently supported directly inthe end of arm III, as shown in Fig. 3. Here, the contact 1 is free tomove in a recess in the end of arm I0, and the contact I is backed up bya coil spring 2| whose travel is regulated by p n adju tment screw 22.In this case, contact I may be connected to slip ring 9 in anyconvenient manner. The operation of the coil spring supported contact issimple, in that after the first touching of contacts 6 and 1 spring 2|compresses until it can compress no further, and thereafter the arm l0operates to drive disc 4.

The switch shown in Figs. 4, 5, and 6 is the reciprocal of the switchshown in Figs. 1, 2, and 3. Here, the sleeve 3 is provided with-a flange24, Arm I0 is mounted on an arm sleeve 25, free to rotate on shaft. 2,and a clutch spring 26 is solidsure, against flange 24. The pressure isdetermined by adjustment of pressure sleeve 21 mounted on the shaft andholding the arm sleeve 25 against the push of the clutch spring.

The base of. the resilient contact I is now mounted on the case Ithrough contact stud 21. and the resilient contact I extends upwardly inthe path of contact 6 which is now carried directly on the end of arm I.Contact 6 is connected by link 29 to slip ring 9, which is contacted, asin the formerly described switch, by slip ring brush M.

A stop pin 38 is now positioned back of resiliently supported contact Iso that it can flex only a definite amount. Inithe operation of thisswitch, when the shaft 2 is rotated in one direction to cause contact 6to approach contact I, arm l0 being frictionally driven by the shaft.the first thing that occurs is that contact 6 touches contact I, butinasmuch as I prefer to adjust the clutch friction to be sufficient toovercome the resiliency of the support for contact I, contact 1 willflex and continue to flex, with contacts 6 and I touching, until contact1 hits stop pin 30. A firm resistance is then ofiered to any continuedrotation of arm l0, and the clutch spring 26 will slip on flange 24 andcontinue to slip during further rotation of the shaft in the samedirection. When, however, the shaft. is

stopped and the frictional pressure removed, the

resiliency of the resilient contact I still causes firm contact betweencontacts 6 and I. Arm l0 may reverse its direction over small arcs ofthe shaft and contact 1 will follow contact 6 until contact 1 reachesits normal position, where it ceases to exert pressure, and with furtherrotation arm to draws away and the circuit through the switch will bebroken.

Here, as in the first switch, in order to prevent contact 6 fromdeparting too far from contact I, a stop pin 18 is positioned on thecase i so that when arm l0, upon reversal of rotation, reached stop pin18, it can travel no further and the shaft 2 may continue to rotate inthat direction. Upon reversal of rotation, contacts 6 and I will againtouch and establish electrical connection through the switch.

In Fig. 6, both contacts 6 and I are resiliently supported, and contactI is backed up by stop pin 30. Here, arm I0 first touches contact 6,picks it up and carries it to touch contact I, which is also picked upand carried until stop pin 30 is reached. Here, a firm opposition isoffered to further rotation of arm III. and the clutch slips with theelectrical connection made. When the shaft stops, the resilientlysupported contact I exerts pressure against contact 6 backed by arm l0until contact I straightens out, whereupon contact 6 will leave it. Theconnection is broken, and contact 6 straightens out asthe arm 10proceeds in its reverse direction until it brings up against stop 18.

.It is clear from the above description that the switches hereindescribed utilize a butt contact. However, these butt contacts differfrom the usual butt contacts in that at least one of the contact pointsis resiliently supported, so that when a second contact pushes againstit the two contacts move as a unit over a predetermined path until astop is reached, the frictional forces operating to keep the contacts inmaking position when the shaft is rotated in one direction and inbreaking position when the shaft is rotated in the other direction. Theresilient support of at least one of the contacts assures that when theshaft is stopped in contact making position there is a firm pressuremaintained between the contacts, and that when there are only slightreversals of direction of rotation of the shaft thereafter, the contactswill still touch, and then will separate cleanly when the making andbreaking forces acting on them are removed.

I claim:

1. In combination, a single shaft, a driving member positively mountedon said shaft, a contact mounted on said driving member, a driven membercomprising a disc mounted for free rotation on and insulated fromsaidshaft and movable only by force communicated from said driving member, acontact on the driven member, said contacts adapted to' form a buttconnection and at least one of the contacts being resiliently mounted inspaced relation to its support along the arc of rotation of said drivingmember, said driven member being driven by the driving member when thetwo contacts have met and the moforsupporting said shaft, frictionalmeans mounted on said casing adapted to cooperate with said driven discmember in torque creating relationship thereto at a point at asubstantial radial distance from said shaft and operating to keep saidcontacts in contact niaking position when said shaft is rotating in onedirection, and in contact breaking position when the shaft is rotatingin the other direction, said frictional means being insulated from saidshaft and also serving as an electrical connection to the driven member,and stop means mounted on said driven member for limiting the separationof the contacts.

2. A combination as defined in claim 1, characterired in thattheresilient contact is mounted on the driving member.

3. A combination as defined in claim 1, characterized in that theresilient contact comprises a movable element adapted to move relativelyto the driving member, and a cooperating spring, both the movableelement and the spring being mounted on said driving member.

HERBERT E. METCALF.

